Clipboard/Copy&Paste Broke – How to fix?

All of a sudden my Copy & Paste function has broken. When I copy a string and then try to paste it, all I get is a single blank. I’m running Win-XP Pro SP2. C&P is broken for IE, Firefox and even Notepad, so it must be a problem deep in the bowels of the OS. MAY BE caused by overly agressive spyware/virus scanning as I do that a lot. Or it might be a bad install of some app. I don’t have a clue how it happened.

I tried searching at the Microsoft Support Knowledgebase and that was no help at all. I tried Google and it retrieved hundreds of hits of a similar Linux problem. If I knew exactly what file(s) might be blitzed I could restore from a recent backup. But I don’t even know where/how to start diagnosing this problem.

Can anyone give me some advise? Hints? Anything?

Thanks in advance. VV